Background The effect of jaw design on grip security and tissue trauma is p
oorly understood. This project establishes an in vitro model of the instrum
ent-tissue interface.
Materials and methods. Aluminum jaws with teeth of differing size and shape
gripped fresh sheep stomach with variable apposing (squeeze) pressure. The
tissue was extracted at a rate of 50 mm/min until either the grip or the t
issue failed, The load at which the grip failed, the maximum (peak) load ge
nerated, and the mode of failure were noted. The data were analyzed using A
NOVA and a post hoc Duncan's multiple range test when appropriate.
Results. Increasing the apposing pressure increased grip security. Grip sec
urity of 1- and 2-mm pitch teeth were significantly greater than for plane
jaws and smaller-pitch teeth (P < 0.001), Of the wave pattern jaws, 2-mm pi
tch waves also had significantly greater grip security than plane jaws and
smaller pitch waves (P < 0.01). Wave pattern jaws produced significantly le
ss tissue trauma than teeth (P < 0.0001).
Conclusions. Increasing the size of instrument teeth increases grip securit
y but at the expense of tissue trauma. Wave pattern jaws result in signific
antly less tissue trauma than teeth. This model measures grip security prec
isely and allows for comparison between jaws of different patterns. (C) 200
0 Academic Press.